As semiconductor devices have become smaller in size, substrates with microstructures (substrates formed with material films that vary in physical properties) are being processed these days. For example, in a damascene interconnect formation process in which wiring grooves formed in a substrate are filled with metal, extra metal is removed by polishing performed by a substrate polishing system (CMP system) after the damascene interconnect formation, and thus, materials films (such as a metal film, a barrier film, and an insulating film) that vary in physical properties are formed on the substrate surface. On such a substrate surface, there are residues of the slurry used in CMP and metal grinding sludge (such as Cu grinding sludge). Therefore, in a case where a substrate surface cannot be sufficiently cleaned, such as a case where complexity of a substrate surface makes the cleaning difficult, leakage or an adhesion defect occurs due to residues or the like, and might result in a decrease in reliability. To counter this, a CMP system that polishes semiconductor substrates conducts cleaning after the polishing. In the cleaning process, pen scrub cleaning or two-fluid jet cleaning is performed, for example (see Patent Literatures 1 and 2, for example).